A data-driven approach for retrieving temperatures and abundances in brown dwarf atmospheres

Michael R. Line, Jonathan J. Fortney, Mark S. Marley, Satoko Sorahana

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

Brown dwarf spectra contain a wealth of information about their molecular abundances, temperature structure, and gravity. We present a new data driven retrieval approach, previously used in planetary atmosphere studies, to extract the molecular abundances and temperature structure from brown dwarf spectra. The approach makes few a priori physical assumptions about the state of the atmosphere. The feasibility of the approach is first demonstrated on a synthetic brown dwarf spectrum. Given typical spectral resolutions, wavelength coverage, and noise, property precisions of tens of percent can be obtained for the molecular abundances and tens to hundreds of K on the temperature profile. The technique is then applied to the well-studied brown dwarf, Gl 570D. From this spectral retrieval, the spectroscopic radius is constrained to be 0.75-0.83 RJ, log (g) to be 5.13-5.46, and Teffto be between 804 and 849 K. Estimates for the range of abundances and allowed temperature profiles are also derived. The results from our retrieval approach are in agreement with the self-consistent grid modeling results of Saumon et al. This new approach will allow us to address issues of compositional differences between brown dwarfs and possibly their formation environments, disequilibrium chemistry, and missing physics in current grid modeling approaches as well as a many other issues.

Original languageEnglish (US)
Article number33
JournalAstrophysical Journal
Volume793
Issue number1
DOIs
StatePublished - Sep 20 2014

    Fingerprint

Keywords

  • brown dwarfs
  • methods: statistical
  • radiative transfer
  • stars: atmospheres
  • stars: individual (Gl 570D)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this